The present invention relates to an adhesive composition that is useful to attach roofing membranes or underlayments to a roof area. Specifically, the present invention relates to an adhesive composition that is pressure sensitive and may be utilized to apply a roofing membrane in a peel and stick manner. Additionally, the present invention relates to a roofing membrane or underlayment having the adhesive composition of the present invention applied to at least one major face.
Roof sheeting materials such as ethylene-propylene-diene terpolymer (EPDM), butyl rubber, neoprene, polyvinyl chloride, chlorinated polyethylene, thermoplastic polyolefin (TPO) and modified bitumen and the like are often used as single-ply roofing membranes or underlayments because they are well known in the art as having barrier properties against moisture. The roof sheeting materials are customarily attached to the roof area using an adhesive. The roof sheeting materials may be exposed to stresses such as roof movement, heavy winds, freeze-thaw cycles and thermal cycles. Therefore, the adhesive must be able to withstand such possible stresses.
Currently, roofing membranes and underlayments are adhered to roof decks or insulation boards utilizing a variety of methods. One such method involves the use of liquid based adhesives that employ natural and/or synthetic elastomers and resins in organic solvent systems. These liquid based adhesives do not always provide good bond strength and long-term durability. For example, if conditions during application are windy, dust or other debris may adhere to the adhesive and impair the quality of the bond. High temperatures may cause the adhesive to dry out too quickly. These environmental problems may complicate installation procedures. Additionally, liquid based adhesives often utilize organic solvents such as toluene and xylene. These solvents pose a health and fire hazard, and their use is undesirable.
Other methods of adhering roofing membranes include the use of slow drying water based adhesives. Additionally, asphalt based adhesives that must be heated to a molten state and then swabbed onto the roofing surface may also be used. However, these asphalt adhesives require special equipment and can pose a fire risk. Heat welding of thermoplastic materials and nailing have also been utilized to secure roofing membranes or underlayments to roof decks or insulation boards. Cover strips, flashings or other accessories have also been secured utilizing these processes. These processes may be extremely time consuming, hazardous or provide an inferior seam.
Thus, there is a need for an adhesive composition that effectively adheres roofing membranes or underlayments to a variety of materials with ease of application. The adhesive should provide high bond strength and excellent long-term heat aging, weathering resistance and low temperature properties while providing a moisture proof seam. Additionally, the adhesive should pose no environmental hazard.
The present invention meets that need by providing an adhesive composition for roofing membranes. The adhesive composition may be applied in a peel and stick manner, and poses no environmental hazard.
In accordance with one embodiment, the adhesive composition includes a) a rubbery polymer comprising a blend of i) a thermoplastic block copolymer selected from the group consisting of a styrene-butadiene-styrene block copolymer, a styrene-isoprene-styrene block copolymer, a styrene-ethylene/butylene-styrene block copolymer, a styrene-ethylene/propylene block copolymer and an ethylene-propylene block copolymer and combinations thereof and ii) a polyisobutylene; b) a compatible tackifier; and c) an amorphous polyolefin.
In a preferred form, the adhesive composition includes a) a rubbery polymer comprising a blend of i) from about 20% or less by weight of the total composition of a thermoplastic block copolymer selected from the group consisting of a styrene-butadiene-styrene block copolymer, a styrene-isoprene-styrene block copolymer, a styrene-ethylene/butylene-styrene block copolymer, a styrene-ethylene/propylene block copolymer and an ethylene-propylene copolymer and combinations thereof and ii) from about 13% or less by weight of the total composition of a polyisobutylene; b) a compatible tackifier; and c) a compatible plasticizer. The thermoplastic block copolymer may comprise about 10-15% by weight of the total adhesive composition, and the polyisobutylene may comprise about 1-8% by weight of the total adhesive composition. The adhesive composition exhibits 180xc2x0 peel strength at room temperature of at least 254 grams/in (100 g/cm) when adhered to a substrate, and the adhesive composition supports a static load of at least 50 grams/in2 (8 g/cm2) at 70 xc2x0 C. for at least 96 hours when adhered to a substrate.
In accordance with another embodiment, an adhesive roofing article having a composition for adhering the roofing article to a roof area is provided. The roofing article has first and second major surfaces. The adhesive composition is applied to the first major surface, and the adhesive composition includes a) a rubbery polymer comprising a blend of i) a thermoplastic block copolymer selected from the group consisting of a styrene-butadiene-styrene block copolymer, a styrene-isoprene-styrene block copolymer, a styrene-ethylene/butylene-styrene block copolymer, a styrene-ethylene/propylene block copolymer and an ethylene-propylene block copolymer and combinations thereof and ii) a polyisobutylene; and b) a compatible tackifier. The roofing article may have a release liner adhered to the adhesive composition.
The adhesive composition of the roofing article comprises less than 20% of the total adhesive composition by weight of the block copolymer less than 13% of the total adhesive composition by weight of polyisobutylene. In a preferred form, the thermoplastic block copolymer comprises about 10-15% by weight of the total adhesive composition, and the polyisobutylene comprises about 1-8% by weight of the total adhesive composition. The adhesive composition exhibits 180xc2x0 peel strength at room temperature of at least 254 grams/in (100 g/cm) when adhered to a substrate, and the adhesive composition supports a static load of at least 50 grams/in2 (8 g/cm2) at 70 xc2x0 C. for at least 96 hours when adhered to a substrate.
The present invention provides an adhesive composition with excellent tack and quick stick properties. The adhesive resists extreme heat and cold. Additionally, the adhesive may be used with a roofing article such as EPDM rubber or TPO to provide a watertight seal. The adhesive may be used in a variety of weather conditions, and no special equipment is required. Additionally, the adhesive poses no environmental hazard and does not require hazardous solvents.
Accordingly, it is a feature of the present invention to provide an adhesive composition for use in adhering together sheets of roofing materials which provides ease of application, good strength, and a long term water tight seal. This, and other features and advantages of the present invention will become apparent from the following detailed description and the appended claims.